o'meara, on diatomacEjE. 75 



lihurnica, var., fig. 8. By the Avord he has omitted, and the 

 letters he has unwarrantably introduced, Mr. Kitton charges 

 me with claiming this designation as my own, Avhereas I 

 attributed it to Grunow, and represented the form described 

 by me merely as a variety of Raphoneis libwnica of that 

 distinguished author. 



Again, at page 16, we read, '' Cocconeis divergens, fig. 5, 

 may be the same," &c. Although no form so named occurs 

 in my papers, that to which I suppose he intended to refer 

 is Cocconeis clavigera, Avhich is so dissimilar in all respects 

 to C. costata of W. Gregory, as well as to Raphoneis At'cheri, 

 it is difficult to comprehend how they could be confounded. 



These inaccuracies, however, although evidences of care- 

 lessness, do not materially affect the judgment pronounced, 

 but the same cannot be said regarding the following mistake. 



Page 14, " In the following observations I have assumed 

 the amplification in the first paper to be the same as in the 

 second, viz., 600 diameters." Now, the amplification in the 

 second jDaper is not invariably 600 diameters, as the words 

 referred to would lead the reader to suppose. In some in- 

 stances, as indicated in the table, it is 800 diameters ; and in 

 the description of the figures, which accompanied the first 

 paper, the amplification is plainly stated to be 400 diameters, 

 and not 600, as was assumed. 



As regards the forms in my papers which have happily 

 escaped animadversion, it is to be presumed they are exempt 

 from objection; and if so, enough remains to attach con- 

 siderable interest and value to the Arran gatherings. 



But as regards the forms which have provoked the censure 

 of Mr. Kitton, Avhat is his judgment, and by what process 

 has he reached it ? 



" The following forms described in Rev. E. O'Meara's 

 papers may, I think, be referred to previously described spe- 

 cies." It is difficult to understand how his remarks on 

 Pinnularia divaricata are reconcileable with this form of ex- 

 p)ression. They are to this efiect. " Pinnularia divaricata, 

 O'M., fig. 7, if correctly figured and described, can neither 

 be a Pinnularia nor Navicula, as none of these genera have 

 forked striae or costse." On the assumption, then, that the 

 figure and description are correct, and 1 can assure him that 

 they are, this form, in Mr. Kitten's opinion, must be sepa- 

 rated from these genera — must, in fact, be assigned to a neiv 

 genus. How incongruous the opinion thus expressed Avith 

 the previous statement, so far as the form in question is con- 

 cerned, " the following forms may, I think, be referred to 

 previously described species.^'' 



